Particles
The smallest particle in physics are
quarks and
leptons, quarks combines to form
hadrons which are protons and neutrons. Proton and neutrons, as well as electrons combine to form
an atom. A group of atoms is called a
molecule.
In an atom,
protons are the particle with a positive charge,
neutrons have a neutral charge and the
electrons have a negative charge and orbits the nucleus of the atom.
Protons and neutrons are made up of 3 quarks. They are also called
baryons. A proton has 2 up quarks and 1 down quark while a neutron has 2 down quarks and 1 up quark. Hadrons made up of 2 quarks
are called
mesons.
Unified Theory of Physics
The theory-of-everything is a physics problem that can unite the four fundamental laws of physics (strong, weak, gravity and electromagnetic). Physicist have been trying to solve for a unified
theory for decades.
The previous three (strong, weak and electromagnetic) can be solved using quantum physics (termed the "standard model") while gravity does not abide by the quantum model and stuck
to the Einsteinian physics of the "General Relativity".
Grand Unified Theory of Physics - Big Think
The Four Fundamental Forces
1. Gravity
2. Electromagnetic
3. Strong nuclear force
4. Weak nuclear force